LT1123CZ#TR Linear Technology, LT1123CZ#TR Datasheet - Page 4

• Manufacturer Part Number: LT1123CZ#TR
• Description: IC LDO REG DRIVER 5V TO-92-3
• Manufacturer: Linear Technology
• Type: Positive Fixedr

Specifications of LT1123CZ#TR

• Number Of Outputs: 1
• Voltage - Output: 5V
• Current - Supply: 700µA
• Operating Temperature: 0°C ~ 125°C
• Package / Case: TO-92-3 (Standard Body), TO-226
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Input: -

SI PLIFIED
FU CTIO AL DESCRIPTIO
The LT1123 is a 3-pin device designed to be used in
conjunction with a discrete PNP transistor to form an
inexpensive ultralow dropout regulator. The device incor-
porates a trimmed 5V bandgap reference, error amplifier,
a current-limited Darlington driver and an internal thermal
limit circuit. The internal circuitry connected to the drive
pin is designed to function at the saturation voltage of the
Darlington driver. This allows a resistor to be inserted in
LT1123
PI FU CTIO S
All internal circuitry connected to the drive pin is designed
to operate at the saturation voltage of the Darlington
output driver (1.4 to 2V). This allows a resistor to be
inserted between the base of the external PNP device and
the drive pin. This resistor is used to limit the base drive to
the external PNP below the value set internally by the
LT1123, and also to help limit power dissipation in the
LT1123. The operating voltage range of this pin is from
0V to 30V. Pulling this pin below ground by more than one
V
This condition can only occur if the power supply leads are
4
BE
W
U
U
will forward bias the substrate diode of the device.
U
U
BLOCK DIAGRA
U
DRIVE
U
W
THERMAL
CURRENT
GROUND
LIMIT
LIMIT
series with the drive pin. This resistor is used to limit the
base drive to the PNP and also to limit the power dissipa-
tion in the LT1123. The value of this resistor will be defined
by the operating requirements of the regulator circuit. The
LT1123 is designed to sink a minimum of 125mA of base
current. This is sufficient base drive to form a regulator
circuit which can supply output currents up to 4A at a
dropout voltage of less than 0.75V.
reversed and will not damage the device if the current is
limited to less than 200mA.
Feedback Pin (V
functions. It provides a path for the bias current of the
reference and error amplifier and contributes a portion of
the drive current for the Darlington output driver. The sum
total of these currents is the Feedback Pin Bias Current
(300µA typical). The second function of this pin is to
provide the voltage feedback to the error amplifier.
–
+
LT1123 SBD01
FB
5V
): The feedback pin also serves two
FB
1123fb